1. Field of the Invention
The present invention relates to the field of optoacoustic tomography. More specifically, the present invention relates to a method of enhancing contrast during quantitative optoacoustic tomography and removing image artifacts using maximum angular amplitude probability (MAAP) reconstruction of an image.
2. Description of the Related Art
Optoacoustic tomography is used in biomedical applications for in vivo and in vitro imaging of animal and human tissues and organs based on differences in tissue optical properties. Optoacoustic tomography has the potential to become valuable modality of functional molecular imaging. The essence of functional molecular imaging is to provide quantitative information (maps) of distributions and concentrations of various molecules of interest for medicine. For example, distribution of hemoglobin and oxi-hemoglobin concentration in tissue shows whether the tissue normally functions or it is damaged or malignant. Distribution of specific protein receptors in cell membranes give insight into molecular biology or cells helping in designing drugs and therapeutic methods to treating human diseases.
Traditionally, a radial back projection (RBP) image reconstruction algorithm is used in a laser optoacoustic imaging system (LOIS) to reconstruct two-dimensional (or three-dimensional) images of the object (such as tumor). Image blurring and the presence of artifacts in form of radiating arcs decrease resolution and clarity of the image. Most importantly, the brightness of objects or area of interest on images reconstructed with RBP is not proportional to the original amount of absorbed optical energy. This occurs due to the fact that each receiving transducer with wide angular aperture can integrate information received from a number of objects in the volume being imaged, so that the brightness of any specific object is altered upon radial back projection of signal amplitudes integrated over the spherical surface within the field of view of each transducer.
Thus, a recognized need is present in the art for improved quantitative optoacoustic tomography procedures. Specifically, the prior art is deficient in methods applying algorithms effective to significantly improve the (1) accuracy of quantitative information displayed on optoacoustic images and (2) contrast of optoacoustic images (relative contribution of image artifacts). More specifically, the prior art is deficient in using maximum angular amplitude probability reconstruction algorithm to provide for clear visualization of real optical absorbers and improved estimation of absorption coefficients of specified discrete absorbers. The present invention fulfils this longstanding need in the art.